The present invention relates to a redundant electrical grounding system.
Every hospital bed has the same hazard of electrocution as a bathtub or swimming pool during the portion of its occupancy when it is wet with perspiration, leakage, or incontinence. The grounded metal stirrups of motorized tables and the wet operating, delivery, and hemo-dialysis rooms are equally hazardous areas. The hazard is increased by the invasion of the patient's body by instrumentation, illness, or intoxication. The patient, usually exposed to only one electrical appliance at a time in the safe, dry, ungrounded environment of the home, is subjected to an assemblage of appliances such as the electric bed, the examining lamp, the suction pump, the refrigerated blanket and the electrocardiograph.
Loss of any grounding circuit due to a defective plug, receptacle, cable, connection, or an improperly wired line cord subjects the patient to dangerous electric shock.
Because interruption of electric power is intolerable, current limiting devices which interrupt current on detection of ground fault current are not acceptable. Isolation transformers are extremely costly and require special low leakage receptacle wiring, appliances and power cables.
The recommended practice is the use of redundant grounding This is accomplished by attaching conductors from each appliance chassis to a grounded terminal plate at each receptacle. This is time consuming and requires the services of maintenance men who may not be available when appliances are installed or removed.
The system of the invention automatically provides redundant grounding, without loss of time or need for maintenance men, when the appliance operator connects the redundant grounding line cord plug into the redundant grounding wall receptacle.
All receptacles of the system of the invention are compatible with conventional three prong and two prong polarized plugs to prevent interruption of service in areas converted to redundant grounding receptacles. In like manner, appliances, manufactured with or converted to the single plug redundant grounding system, may be utilized on conventionally grounded receptacles with the use of an inexpensive adapter .